Oncidesa - Discolored but firm pseudobulbs - rot? viral?

[merbyderby]

I have had this Oncidesa Hwuluduen Chameleon for over a year now, and it just rebloomed. Within just the last few days, the two newest pseudobulbs have become very discolored. I immediately thought it was rot but they're totally firm, no soft spots.

I water when just dry, they have fans running in the cabinet and humidity is around 50-60%.

I'm secretly hoping that someone will say this is somehow nothing, but prepared for surgery if needed! Mostly I'm also wondering if this is rot, viral, or how I could prevent in the future.